Thermostatic switch



July 16, 1935. E. WALDER THERMOSTATIQ SWITCH Original Filed Jan. 50, 1932 ATTORNEY.

Patented July 16, 1935 UNITED STATES PATENT OFFICE 2.008.183 I THERMOSTATIC swrrcn Original application January 30, 1932, Serial No.

589,814, now Patent No 28, 1934. Divided and 1,971,971, dated August this application September 3, 1932, Serial No. 631,622

4 Claims.

In my parent application Serial No. 589,814, filed January 30, 1932, which became Patent No.

1,971,971, August 28, 1934, I have described and broadly claimed a novel thermostatic heat control for electrical appliances.

My present application which is a division of my parent application aforesaid, relates more particularly to the novel construction and arrangement of the thermostatic switch which is capable of general application and may be applied to any desired electrically heated appliance.

With the above in view, my invention comprehends a novelconstruction and arrangement of a thermostatically controlled switch and novel means for manually setting the switch so that it will be opened and closed at predetermined temperatures of the heating appliance to which the thermostat is operatively connected.

Other novel features of construction and advantage will hereinafter appear in the detailed description and the appended claims.

For the p pose of illustrating the invention, I have shown in the accompanying drawing a typicalembodiment of it, which, in practice, will give satisfactory and reliable results. It is, however, to be understood that this embodiment is typical only and that the various instrumentalities of which my invention consists can be variously arranged and organized, and the invention is not limited to the precise arrangement and organization of these instrumentalities as herein set forth.

Figure l is a sectional elevation of a thermostatic switch employing my invention, illustrated in conjunction with a portion of an electric heating appliance, shown, for purpose of illustration, as a portion of a wafile iron.

Figure 2 is a side elevation of the switch in conjunction with a supporting grid shown in section.

Figure 3 is a bottom plan view ofthe switch and the grid which carries it.

Figure 4 is a sectional view through the relatively stationary contact carrying member showing more particularly the manner in which it is insulated from the means employed to adjust its setting.

Figure 5 is a section on line 5-5 of Figure 1.

Similar numerals of reference indicate corresponding parts.

Referring to the drawing:-

My present type of thermostatic switch is illustrated in conjunction with a conventional waiile iron which, as is well known, is provided with a sectional casing having upper and lower sections hinged together. Each of the sections is provided with a grid having, as illustrated, complementary recesses and lugs of any desired formation for forming a waflle iron. The lower grid I has secured to it a disc 2 by means of fastening devices 3 which also pass through a sheet of asbestos 4. The disc 2 is preferably centrally recessed as at 5 to provide for the movement of the thermostatic element 6 which is preferably formed of bi-metallic strips. This element 6 is fixed at one end with respect to the grid I by means of a fastening device 1. The disc 2 has depending from it apost 9 illustrated as in the form of a screw which serves as a mounting for a flexible metallic strip 9, and a flexible metallic strip l9, each of such strips forming a contact carrying member. The strip 9 has secured to it, near its free end, the relatively fixed contact H, and the strip III has secured to it, near its free end, the relatively movable contact l2 which cooperates with the relatively fixed contact I I. These two contact carrying members 9 and iii are secured in spaced relation on the post 8 and are insulated from each other. The post 8 passes through a lava washer l3 interposed between the disc 2 and the contact carrying member 9. A lava washer H is interposed between the contact carrying members 9 and I9.

A mica washer I5 is disposed beneath the contact carrying member I0. Then comes a brass washer l6 and the parts are secured in assembled condition by means of a nut I! in threaded engagement with the post 8. The contact carrying members are apertured to permit this post 8 to pass therethrough and these apertures are of greater diameter than the diameter of the post so that the contact carrying members are retained in spaced and insulated relationship. The movable contact carrying member I 9 carries an adjusting screw i8 in threaded engagement with it and provided with a lock nut l9. The adjusting screw l8 passes through an aperture 20 in the contact carrying member 9 and also through an aperture 2| in the disc 2 and has its free end in the path of the thermostatic element 9 so that when the temperature of the grid l increases, the thermostatic element 6 will deflect downwardly until it contacts with the adjusting screw l8. On its further deflection, it will move the free end of the contact carrying member I 9 downwardly to eflect the separation of the contacts l2 and II and thereby open the electric circuit.

The free end of the contact carrying member 9, see more particularly Figure 4, is apertured to receive the shank of a rounded button 22. This shank passes through an insulating washer 23 and through an insulating washer 24 and through a metal washer 25 and is provided with a nut 26. It will be clear that, from this con-4 struction, the button 22 is insulated from the contact carrying member 9.

21 designates a cam which contacts with the button 22 and is pivotally mounted at 28 on the disc 2 of the heating unit. This cam 21 is provided with an arm 29 which passes through a slot 30 in the lower casing section of the heat ing appliance and is provided with a relationship to indicate the different degrees of temperature of the heating appliance.

. See Figure 3.

tact carrying member 9 has a conductor 35 leading to the binding post 36 to which is connected the resistance wire 31 located in the groove 38 in the disc 2. This resistance wire is imbedded in the disc 2 and connected-toa binding post 39, A conductor 40 leads from the binding post 39 to the binding post 4| and resistance wire 42 of the upper heating element and returns to the binding post 43 which is connected by means of a conductor 44 with the prong 45 of the electrical appliance.

The operation of my novel thermostatic switch will now be'apparent to those skilled in this art and is as follows:

The prongs 33 and 45 are connected in the usual manner with a source of electric supply. The position or setting of the relatively stationary contact H is produced by rocking the cam 27 by means of the handle 3| into a position which corresponds to the degree of temperature at which the circuit is to open and close. When the button 22 is on the low point of the cam, the movement of the heat responsive element, formed by the thermostatic element 6, will not be sumcient to move the screw I8 to efiect the separation of the contacts I l and I2 and thus open the circuit.

It will be apparent that in the position seen in Figure 2 the free ends of the contact carrying members have both been moved downwardly, the contact carrying member 9 by the cam 21 and the contact carrying member I 0 due to the element 6 moving the screw l8 downwardly so that the contacts II and I! are separated and the circuit is opened.

It will thus be apparent that the circuit will be automatically opened and closed at the degree of temperature for which it is manually set.

It will be apparent that in accordance with this invention the heat responsive element acts directly against an adjusting member which is carried by one of the contact carrying members, for example, the one which carries the relatively movable contact to move it out of contact with the relatively stationary contact on the other contact carrying member. Each of these contact carrying members is flexible, and the one which carries the relatively stationary contact can be manually positioned as may be desired in order to vary the degree of temperature at which the circuit will be opened and closed.

I preferably employ a manually actuated cam to flex one of the contact carrying members to change the position of its contact.

It will be apparent that by proper adjustment of the adjusting screw the heat responsive element will flex to a greater or lesser degree as may be desired before the electric circuit is opened.

Each of these contact carrying members are preferably made of spring metal so that the contact carrying member which carries t he relativ'ely movable contact will quickly re it into contact with the relatively stationary contact.

It will now be apparent that I have devised a new and useful thermostatic switch which embodies the features of advantage enumerated as desirable in the statement of the invention and .the above description, and while I have, in the present instance, shown and described a pre- Ierred embodiment thereoi -which will givein practicesatisfactory and reliable results, it is to be understood that this embodiment is susceptible of modification in various particulars without departing from the spirit or scope or the invention or sacrificing any of its advantages.-

Having thus described my invention what I claim as new and desire to secure by Letters Patent, is:

1. In a thermostatic heat control for electrical appliances, a casing, contact ca rying members in the form of metal strips mounted at one end in spaced and insulated relationship, cooperating contacts on said members, a heat responsive element, an actuating element connected with one of said members and in the path of said heat responsive element to be moved thereby to open an electric circuit, a rounded element on one of said members and insulated therefrom and a rotatably mounted manually actuated cam cooperating with said rounded element to vary the position of its member relatively to the other contact carrying member.

2. In a thermostatic heat control for electrical appliances, a casing, contact carryin members mounted at one end in spaced and insulated relation one above the other with their free ends extending in the same direction, a relatively stationary contact carried by one member, a relatively movable contact carried by the other member and actuatingmembers adjustably carried by one of said contact carrying members and extending beyond the other contact carrying member and adjustable to vary the time interval for the closing of the circuit, a heat responsive device bearing against said actuating member, a metallic element carried by but insulated from the stationary contact carrying member, and a manually actuated cam cooperating with said metallic element to vary the position of the relatively stationary contact.

3. In a thermostatically controlled switch, two flexible contact carrying members, cooperating contacts carried thereby, a heat responsive member, means to secure said members at one end in insulated and spaced relationship, a set screw carried by one of said members and extending beyond the other contact carrying member into the path of said heat responsive member, and locking means for said set screw.

4. In a thermostatic switch, a support, a heat responsive element, a pair of flexible metallic contact carrying members carried at one end of said support in spaced and insulated condition, an adjusting screw carried by one of said contact carrying members passing beyond the other contact carrying member and through the support into the path of movement of the heat responsive element, contacts for said contact carrying members, and manually actuated means to move one of said contact carrying members to change the location of its contact relatively to the contact carried by the other contact carrying member,

EMIL WALDER. 

